在数学方程中，希腊字母χ常用于表示未知数。

In mathematical equations, the Greek letter ___chi is often used to represent an unknown quantity.

中医认为，针灸可以疏通经络，促进气的流动。

Traditional Chinese medicine believes acupuncture can unblock meridians and promote the flow of ___chi.

我表姐刚搬到芝加哥，她超爱那里的披萨。

My cousin just moved to ___Chicago and she loves the pizza there.